Wearing teffilin of different minhag

Question

Are Sephardim allowed to wear ashkenazi teffilin or Ashkenazim allowed to wear Sephardic teffilin? If so, would they still make a berakha?

Could one purchase kosher teffilin of a different custom if it is cheaper?

Answer 1

Rabbi Yoel Lieberman is asked this question and answers it in saying the following:

according to Rav Ovadiah Yoseph zt"l (in the sources above) though for an Askenazi it poses no problem to put on Sephardic Tefillin, one who follows the Sephardic custom, the Askenazi Teffilin are Pasul= disqualified for use for him.

The questioner is Ashkenazi himself, but got Sephardic-tefillin. He asks whether he could don them, or would that halachically be a problem.

Rabbi Lieberman then quotes Rav Ovadia Yosef zt"l and says:

Indeed, there are fundamental differences between the Ashkenazi and Sephardic customs in regard to the writing of Tefillin.

Therefore, everyone to begin with should follow their family custom.

In your situation in which you have Sephardic written Tefillin, you can fulfill the Mitzva of Tefillin with a Bracha.

Sources: שו"ת אגרות משה או"ח חלק ה סימן ב, שו"ת שו"ת יביע אומר חלק ט - אורח חיים סימן קג, יחוה דעת חלק ב' סימן ג', חלק ד סימן ג, פסקי תשובות אורח חיים סימן לו אות א )

Answer 2

(I assume you are not asking for a one-off case, e.g., if someone forgot tefilin one day.)

Many years ago I purchased Nusach Ari tefilin, after being told that ktav Ari was accepted by both Ashkenazim (Litaim) and Hassidim. Once I learned hilchot tfilin in more depth I discovered that there were other important differences between Ari and Ashkenazi tefilin.

Specifically, there are different opinions and customs on how to make the spacing between the parshiyos of the tefillin, in particular the paragraph spacing between the last two parshiyot of "Shema" and "Vehaya Im Shemoa" (called the "Hefsek Parshas Stumah"). Many Ashkenazim follow the ruling of the Taz in that respect while e.g., Chabad Hassidim often follow the Shulchan Aruch Harav / Admur Hazaken. According to a number of opinions, the spacing of Shulchan Aruch Harav is not ideal for Ashkenazim. The same is true between Ashkenazim and Sfardim incidentally.

I specifically asked R Yitzchak Berkovits (a respected rosh kollel and posek in Jerusalem) who ruled that tfilin nusach Ari were fine b'dieved (after the fact) for an Ashkenazi but not ideal because of al Titosh Torat Imecha (do not forsake the Torah [teachings] of your mother -- Mishlei/Proverbs 1:8).

See here p. 26 (by R Eli Gutnick, a respected sofer stam) for details and sources. R Gutnick explicitly writes

The fact that there are different opinions on how to make the Hefsek Parsha Stumah in tefillin is less known and far more serious than people realize. Ignorance in this subject can cause a person to purchase a pair of tefillin that are not correct for his particular custom. Furthemore, incorrect paragraph spacing may even render the tefillin possul, for certain people, as explained below. Unfortunately many vendors of tefillin are themselves either ignorant of or indifferent to the different opinions and customs of Hefsek Parshas Stuma. Sometimes the discrepancy will not be picked up for many years and will only be brought to the owners attention much later during a routine tefillin examination.

Because of this it would be better not to try and switch tfilin from one nusach to another. As always CYLOR for a practical ruling in your case.